Rotor out, hidden disconnection of battery, 4 wheels off and up on jacks, lock it up in the garage and, finally, let the neighbour (old sticky beaak) know where we are going and for how long. This routine grows as I find more little tricks (thanks for the above). An early model restored GTS Monaro got knocked off nearby a couple of months ago in my area, which increased the paranoia levels a bit!

On the plains of hesitation bleached the bones of countless millions.......

All that has already been said above, But i'd also jack the car up with the trolly jack, and move the car o a diagonal angle in the garage, so that it has to be jacked up and moved in order to get the car out again. (and hide the jack of course!!!)

Disconnect the battery anyway- its bound to go flat anyway! And don't leave the handbrake on- I drove the XT recently after it had been sitting for 6 weeks and the rear beakes had temporarily seized on.

For storage of a couple of months or more, i'd pour some motor oil down the carby with the engine running until a little smoke comes out the exhaust (to put oil on the bores to stop corrosion). Id also leave all doors/ boot etc on first catch, not fully closed, so as to not squash the rubbers. Tape up exhaust tips and carby barrel to stop moisture getting into the motor.

Strap a 44 magnum underneath the dash,barrel 8'3/4" pointing backwards, full rifleload hollowpoint in it, and link it with the "loud" pedal "make my day, PUNK steal my ride!
She ain't going far ,but start looking arround for a new rear window, plus rubbers and some serious cleaningproducts.
WHATEVER YOU DO LOCK THE DOORS!
Only said in jest,so do NOT take this serious, as this is not the way to go about it, but sometimes these lowlives get to your sanity.